Improving Papermaking Process by Controlled Modification of Pulp Carbohydrates, 2009 TAPPI Engineering, Pulping, Environmental Conference

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Effects of carbohydrate composition on flocculation, drainage, wet web tension, drying rate, and end-product quality of bleached birch kraft pulps were examined by laboratory handsheets and in pilot former trials. Carbohydrate composition of unrefined and refined never-dried birch pulps were modified with cellulases and hemicellulases. Dewatering, wet web tension, and drying characteristics of the modified pulps were analysed using versatile analytical instruments. Pilot former enabled on-line monitoring of chemical and physical state of the process. Flocculation of fibre suspension was measured on-line with CCD cameras from the headbox of the pilot former. Flocculation results were accompanied by dry sheet formation measurements. Enhanced initial dewatering by modification of carbohydrates was observed in pilot former. Depending on the modified carbohydrate, i.e., xylan or cellulose, and the extent of the enzymatic treatment, the tensile strength of wet sheet samples increased or decreased. Drying rate was noticed to increase due to specific modification of carbohydrates. Enhanced dewatering, tensile strength, and sheet smoothness could be simultaneously achieved by controlled modification of carbohydrates. Modification of carbohydrates of bleached birch pulp had significant influences on all paper-making sections of paper machine.